THE HUSBANDRY OF THE CANE. 



single mould board plough. This plough throws a slice of earth on either side 

 of the share, and finds an extended use in the sugar industry in forming the 

 furrows in which the cane is planted, in opening irrigation channels, in 'bursting 

 out' the middle of the cane rows, and in turning over weeds between the rows 

 in young canes. 



Disc Ploughs. The essential part of the disc plough (Fig. 30} is the 

 revolving discs ; these are of concave shape and revolve about their centre ; 

 the slice of soil is turned over by the action of the concavity of the disc. 



The disc principle was originally devised to lessen the draft on the plough 

 and these ploughs find use in tenacious soils, where the mould board plough 

 will not scour properly, and in very hard lands where it is not possible to use 

 the latter plough. In open loose soils the disc ploughs are inferior to the other 

 type. 



FIG. 30. 



By the use of two discs inclined towards each other, they may be used for 

 furrowing, and they also find one of their most extended uses in turning over 

 and burying the pea vines grown as a green manure. 



Steam Ploughs. This term applies only to the power by which the 

 plough is operated, the latter remaining essentially the same in principle as 

 already described ; instead, however, of there being only one plough, a number 

 are combined into one implement, the whole forming a gang ; as many as seven 

 may be united in one gang, the ploughs being either mould board or discs. 

 T wo methods of applying power may be distinguished ; in one the plough is 

 hitched directly to the engine which draws the plough across the field. In 

 the other two engines are required ; these are located on opposite sides of the 

 field ; each engine is furnished with a winding drum, and through the agency 



105 



